Only 3% of the House of Lords are Spriritual Members so I would think that would make the religious make up of the House a smaller issue than the existence of the unelected House itself.

Well, maybe, but there are such things as matters of principle. That 3% toehold maintains the principle that the Church has a role in governing the nation. I don't like that very much because not only am I not a member of that church but also I oppose its influence, which is predicated on delusion. They may often be nice chaps with a benign veneer who often say good things, even against Tories, but they are only there because they believe in Jesus and seek to spread his good news (the fact that he probably never existed is beside the point, of course). Principles are important: suppose you were defending the royal family to me, a staunch republican, with the argument that the amount they cost us to keep them in the manner to which they're accustomed is minuscule set beside the revenue they bring in from tourism, etc. (as it happens, I disagree with that in any case). You'd be setting aside the whole pyramid of unearned privilege that they represent and sit atop, which is used tacitly to justify inequality in society. In other words, little things can matter a lot.